Synthesis of Hyperbranched Polyisobutylenes by Inimer-Type Living Polymerization. 1. Investigation of the Effect of Reaction Conditions
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Bibliographic record
Abstract
Hyperbranched polyisobutylenes (PIBs) have been synthesized by carbocationic copolymerization of an inimer ( ini tiator-mono mer, IM ) and isobutylene (IB). The IM used was 4-(2-methoxyisopropyl)styrene ( p -methoxycumylstyrene, pMeOCumSt), in conjunction with TiCl 4 as a co-initiator in methylcyclohexane (MeCHx)/methyl chloride (MeCl) 60/40 v/v solvent mixture at −80 °C, in the presence of 2,6-di- tert -butylpyridine (D t BP) as a proton trap. The effect of reaction conditions on the molecular weights (MW), molecular weight distributions (MWD), and branching frequencies (BR) was investigated. Hyperbranched PIBs with MWs up to M n ≈ 8 × 10 5 g mol -1 and MWD as low as 1.2 were obtained within 15−60 min reaction time, where under the same conditions the 2-chloro-2,4,4-trimethylpentane (TMPCl) monofunctional initiator would have yielded MWs in the range of M n ≈ 10 4 g/mol. BRs were determined by selective destruction of the branching points (links) and taking the ratio of the MWs before and after link destruction. The experimental BR values, ranging from 3 to 57, agreed reasonably well with values calculated using the formula BR = ( M n / M n(theo) ) − 1, where M n is the total MW of the hyperbranched PIB, and M n(theo) would be the MW if the IM would act as initiator only. The process was scaled up to 400 g of PIB/batch, sufficient for meaningful physical characterization.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it